Poles for supporting luminaires for the illumination of roadways, parking lots and the like differ not only in that they have either a vertical end with a mast arm or an inclined end, but also in that the diameters of the poles vary. For example, some poles have approximately a horizontal end, the end often being at an angle of 5.degree. to about 15.degree. to the horizontal. This variety of pole construction results in that luminaires are commonly manufactured and warehoused in a corresponding variety of constructions. Accordingly, it would be advantageous to have a universal mounting device for mounting a luminaire to a pole or mast arm.
Additionally, current maintenance costs associated with roadway luminaires is extremely high. Particularly, maintenance is usually performed by licensed electricians to replace capacitors, ballasts, photoelectric controls, starters and complete luminaires. The average cost to replace/install a luminaire is approximately three times the cost of the luminaire itself, e.g. the cost of three men, two trucks and a trailer. There have been efforts in the past to overcome some of the maintenance problems associated with roadway illumination. For example, U.S. Pat. No. 4,937,718 discloses a roadway luminaire having the electrical components employed in the lamp ballasting circuitry mounted to a door member by means of a universal mounting bracket having a deformable planer construction. In this way, a variety of different sized components can be mounted using the disclosed bracket. Additionally, U.S. Pat. No. 4,538,217 discloses a flood light luminaire having all the electrical components mounted on a removable door casting to allow for servicing and maintenance. U.S. Pat. No. 4,791,539 discloses a luminaire having quick-disconnect components which are mounted on an electrical plate detachably secured to a support plate of the luminaire. The plate includes a quick disconnect for detaching the electrical plate from the support plate. However, maintenance of the luminaire is still costly and replacement of components of the ballasting circuitry is difficult and time consuming.
Another disadvantage of known roadway luminaires includes the possibility of replacing a luminaire with one of a different voltage. Currently, roadway lighting may be operated at voltages of 120, 208, 220, 230, 240, 277, 347 and 480 volts throughout the world. Accordingly, it is quite possible when replacing or repairing luminaires to use replacement parts rated for a different voltage. Thus, it would be advantageous to provide a luminaire which includes a means for keying the luminaire so that it can only be replaced by a luminaire which operates at the same voltage.
Yet another disadvantage of known roadway luminaires is the "hot wiring" of the luminaire, thus making replacement difficult and dangerous. In most cases, rather than shutting off the power to the roadway lighting, the lighting is repaired with power being supplied to the luminaire. Accordingly, only licensed electricians with proper protective gear generally perform replacements of luminaires. Thus it would be advantageous to have a luminaire which can be safely and easily replaced even with power being supplied to the luminaire.
In view of the present disadvantages of currently available roadway lighting devices, it is desirable to redesign the luminaire to be easy to install and maintain, provide a fool-proof replacement system which permits only luminaires of same voltage to replace a damaged luminaire and to make installation and maintenance more cost effective.